This used to be an easy question to answer and a lot of the advice still holds true today. A larger tank tends to be more stable and holds more fish – this can be important when some of the most common mistakes involve overstocking or rushing the maturation phase. Aggression between tank mates is less of a problem as tank size increases and species which need to be maintained in shoals to avoid compatibility issues are more readily housed. Many people find that their new aquarium is the gateway to a new and consuming passion and quickly wish that they had more room to house their collection.
With the advent of improved technology and the fashion for smaller tanks, it’s only fair to state their biggest advantage: they’re easy to work with. Consider the advice of having to perform a weekly water change of anything up to 25%, in a large aquarium that’s a lot of heavy water to move about, whereas a smaller system can be serviced with far less time and effort.
That said, after many years of dealing with vast numbers of passionate fishkeepers, most never seem to have enough room for the large selection of interesting species available to this fascinating hobby. Therefore, we would always recommend going for the largest possible aquarium that you can house and afford!